PROJECT SUMMARY Hydroxyurea is a once-a-day oral medication that reduces hospitalizations, transfusions, and medical care costs among patients with sickle cell disease (SCD). Despite these positive benefits, hydroxyurea is not widely used, which reduces the clinical benefits of the drug. The main factors include misperceptions by patients and providers regarding the risks and benefits of hydroxyurea and patients?difficulty in remembering to take the medication. Our long-term goal is to foster increased use of hydroxyurea among patients with SCD through the use of mobile technology. Our initial approach in Aim 1 is to fully understand all factors influencing the initiation or continuation of hydroxyurea therapy by patients, families, and providers. For this, we will interview patients, families, providers, and analyze Medicaid, Medicare, and commercial payer data. We will link the data from the medical system (payer data), with that of individuals, families, and providers. We will identify the reasons hydroxyurea is started and continued. Next, in Aim 2, we will develop and test a new cellular phone text messaging application that will help patients stay on hydroxyurea. We will seek input from patients inquiring about their preferences and perceptions of useful features of a new text messaging application. We will then test this new text messaging application in a group of adolescents and adults in Memphis. We will pay particular attention to how providers and patients see the importance of this intervention and how well it works to improve the effect of HU treatment, such as, improvement of laboratory measures, quality of life. We will then further improve the application based on these initial results. Lastly, in Aim 3, we will expand the testing of this new text messaging application in a large randomized study of patients in different geographical areas of the country. We will study how well it is adopted by patients and providers, how much it changed the patients? perception regarding the difficulties in taking their medication, its costs, and how well it worked to increase HU clinical benefits. Throughout our study, we will use the RE-AIM (Reach, Effectiveness, Adoption, Implementation, and Maintenance) implementation science model to help us measure the large-scale impact of text messaging in the treatment of patients with SCD with hydroxyurea. Ultimately, it is the goal of this project to provide evidence for an effective, low cost, and accessible mobile health technology (cellular phone text messaging) that will lead to better usage of hydroxyurea and improvement of overall health outcomes of individuals living with SCD.